1. Field of the Invention
The present invention relates to ring type supports and drives for silo unloaders.
2. Prior Art
Silo unloaders which utilize a support ring mounted in the silo have been known in the prior art. In most of these, some type of a drive wheel that engages the ring is used either a gear or toothed wheel, or a friction wheel. U.S. Pat. No. 3,912,090 illustrates a support ring that is suspended in the silo, and an unloader is supported on rollers relative to the ring. The unloader is driven through the use of a sprocket type drive wheel as shown in FIG. 6 of this patent. Problems which can occur with this type of drive are quite obvious, in that the ring will tend to deflect, and the drive sprocket may slip, and also the cost of forming the ring with holes punched through it for the drive wheel is quite high.
Another type of support ring is shown in U.S. Pat. No. 2,678,241 which illustrates a ring that has a silo unloader supported on rollers, but wherein the drive for the silo unloader is through the use of a wheel that engages the surface of the silage being unloaded.
Another type of ring type silo unloader wherein the silo unloader is driven through a chain arrangement with the drive motor staying stationary to rotate the gathering mechanism is shown in U.S. Pat. No. 2,580,306 issued to Leach et al. In this device, it can be seen that the drive will be subjected to relatively high loads because the direct drive to the rotating mechanism is from a relatively small diameter drive sprocket. The chain tension necessary for rotating the unit is therefore also quite high.
A silo unloader which has a support ring that is supported from a single cable, and has an upper framework attached to the ring is shown in U.S. Pat. No. 3,146,899. In this device, a friction drive wheel is used against the ring, and friction drives in a silo environment cause a good bit of problem.
Similar devices that show the state of the art include U.S. Pat. No. 3,368,703 which shows a toothed drive, and support rollers on a centrally supported large diameter ring which is suspended from a plurality of cables. A friction drive ring is shown in U.S. Pat. No. 3,612,617, and a typical center unloading silo unloader which can be also used for leveling and filling is shown in U.S. Pat. No. 3,075,657. Other examples of prior art silo drives include the patent to Cordis, U.S. Pat. No. 2,445,056, which illustrates a chain type drive for a silo unloader wherein the chain again directly drives from a stationary motor to rotate the silo unloader.
U.S. Pat. No. 2,963,327 also shows a device having a center ring supported from cables using a toothed drive wheel, as does U.S. Pat. No. 3,473,677. In U.S. Pat. No. 2,701,652 a support ring which has toothed sockets on its top flange is shown. The drive sprocket therefore rotates about a horizontal axis for driving.